According to the relevant GPS codes of our country, the method of loop closure checking is used to calculate 3D coordinate components separately. While in Trimble Business Center (TBC) software, the method of loop closure checking is to calculate the horizontal and vertical components separately. How to calculate the loop closure with 3D coordinate component mode and how to distinguish simultaneous loop and independent loop is an important issue for implementing the required Code under TBC software. The paper is to discuss how to design the GPS field data quality program to solve the problem.